In a galaxy, far, far away...

Robyn Preston

Perth astronomers have witnessed a rare black hole "feeding frenzy" event, only the second of its kind to be seen outside of the earth's solar system in neighbouring galaxy "Andromeda".

The discovery of the "stellar mass" black hole was made using earth-orbiting X-ray satellites, as part of a global study which included scientists from the Curtin University node of the International Centre for Radio Astronomy Research.

Scientist at Perth's Curtin University have observed a rare black hole "feeding frenzy".

Dr James Miller-Jones from Curtin University, ICRAR said observations of the black hole "feeding frenzy" had revealed new insights into the behaviour of the phenomena and would add to the world's limited knowledge of black holes.

A "feeding frenzy" or "binge" occurs when a black hole "swallows material as fast as it can", Dr Miller-Jones said.

"These outbursts are caused when a large quantity of matter falls into black hole. As it falls in, it gets hot and gives off X-rays, which we can see with radio telescopes," he said.

Dr Miller-Jones led the Perth team, who he said were "lucky to look at the galaxy when they did" to see the X-ray emissions from the black hole - located 2 million light years away – which brightened and faded over the course of six months.

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"The team has been observing our nearby Andromeda galaxy with X-ray telescopes on and off for several years now, and when we looked last January, we saw a very bright new source of X-rays," he said.

"Originally there was nothing there and then it got very bright, which lasted for a few weeks, before gradually fading."

The research gained from the rare "feeding frenzy" event will help scientists to solve questions about the size of different black holes that have been observed in other galaxies.

Scientists were unsure whether black holes located elsewhere were big black holes "feeding" at a slow-rate, or smaller masses "feeding" on gas at a high-rate and "faking" the appearance of being larger.

"Astronomers have been studying black holes for several decades now, and have found two main types; 'stellar-mass' black holes, which are just a few times the mass of the sun, and 'super-massive' black holes, which are millions of times the mass of the sun, and are found at the centers of galaxies," Dr Miller-Jones said.

"Seeing the radio waves confirmed that this [new discovery] was just a normal, 'stellar-mass' black hole that was feeding at its maximum rate. We think it is about 10 times the mass of the sun."

Dr Miller-Jones said this discovery provided scientists with a new measure to study black holes.

"Proving that this black hole was one of the lightweight 'stellar-mass' black holes is exciting," he said.

"By demonstrating that this one is a lightweight black hole, it suggests that many of these other bright X-ray sources in other galaxies are also normal, run-of-the-mill, 'stellar-mass' black holes."

While four black hole "feeding frenzy" events have already been observed in earth's own galaxy, the "Milky Way", scientists have found it hard to see and understand what is occurring due to dust and gas that acts like "smoke drifting across in front of a light and blocking it out," Dr Miller-Jones said.

"By finding this source outside our Milky Way galaxy, we don't need to look through all the dust and gas, so can see much more clearly what is going on."

Dr Miller-Jones said that Perth's contribution to the discovery was significant because it showcased some of the new and cutting-edge research that can be performed with state-of-the-art radio telescopes.

"Western Australia is home to two groundbreaking new radio telescopes; the Australian Square Kilometre Array Pathfinder and the Murchison Widefield Array, both of which have recently been opened in the Murchison region of Western Australia," he said.

"We anticipate more incredibly exciting science from these facilities over the coming years."